Can't get Encore to produce a valid DVD image

Question

I've got a project with about 6 menus and 7 timelines - one ~2 hour feature, and several 1-2 minute 'extras'. Menus have simple 30 second looping background videos. Nothing really special...
I've set all my videos to transcode to a custom preset I created:
Video:
Quality: 5
Progressive scan
CBR - 6mbps
GOP: 3, 12
Audio format: MPEG
224kbps
I've manually transcoded all the videos (originally AVI files encoded with Microsoft DV codec from Premiere) prior to Building the DVD. No errors detected in Check Project.
When I create an ISO image of the project, Nero gives me a whole bunch of errors when burning, and results in an unreadable disc.
When I create a DVD folder (VIDEO_TS) and try opening the folder in PowerDVD, it appears to be loading the DVD for a second, but then it just stops (says 'Stop' in the corner). I click 'Play' and the same thing happens. No image whatsoever.
If I get the DVD folder and burn a disc with Nero (as opposed to burning the ISO), I still get errors and an unreadable disc.
HELP! I just created a disc a couple of weeks ago and it worked fine (a completely different project).

Answer 1

CSS has to be added at replication, and cannot be burned to a disc under any circumstances in a form that is playable. It will simply not work.
Non copy protected discs will use blocks of 2048 sectors, and CP discs will use 2054 sectors.
I strongly suspect that this is the main root cause of your troubles here.
To test this theory, write the folder
i without the CSS ticked
and try again. My guess is that it will work.
I can think of another 2 possibler issues here as well:
1 - Nero. It really is garbage for DVD-Video written from folders. There is a well-known issue with the IFO & BUP files being placed too close together, resulting in an image where the player (software or set top) cannot tell there are both files present. I do not know if this has been fixed yet or is still broken. Nero is safe ONLY for burning from images.
2 - You don't mention if your project is PAL or NTSC. From the use of MPEG audio, I will hazard a guess at PAL - MPEG audio is an optional format only in NTSC, and even in PAL these days it's support is optional only & not mandatory. It never was mandatory in NTSC, so unless your disc also includes either LPCM or Dolby Stereo at least then you are out of spec too.
As it happens, there is actually a way to write a disc with the CSS flags set. It involves taking the folder, and turning it into a DDP image though, and to do this you MUST have CSS flags turned OFF in Encore and then write a folder. Launch GEAR Pro Mastering Edition, create a new DVD-Video disc, and turn CSS ON before importing the Video_TS folder. write this to a DDP image on your HDD, and then write that DDP image directly to the root of a DVD-ROM project along with the DDPID file & the CONTROL.DAT file, as well as the IMAGE.DAT file.
That should work instead of a DLT tape.
But you can completely forget using CSS flags to a folder and burning to disc - it will simply never work.
CSS is a scrambling system, royalty free, and all you do at authoring is turn on a flag that tells the replication house you wish this added. They will add the encryption as well as the keys to the final replicated disc. It cannot be done by the author.
(FWIW, it's also a complete waste of time & effort. If you really want to use CP, then a combination of Sony's ARcoSS and SecuRom for the ROM content is the way to go, IMHO.)